I think the reason it appears to work in Artisteer itself is just because of the filler content in the page that is not really part of the design but is enough content to make the page look full height, we are using the css exported from Artisteer so it should work the same but may not appear the same unless there is sufficient content on the page.
There are ways of achieving 100% height, if you google for "css height 100 percent" you can find tutorials and discussions about it.